In a typical prior art magnetic disk recording system a slider containing magnetic transducers for reading and writing magnetic transitions is supported by a suspension as it flies above the disk that is being rotated by a spindle motor. The disk includes a plurality of thin films and at least one ferromagnetic thin film in which the recording (write) head records the magnetic transitions in which information is encoded. The magnetic domains in the media on can be written longitudinally or perpendicularly. The read and write head portions of the slider are built-up in layers using thin film processing techniques. Typically the read head is formed first, but the write head can also be fabricated first. The conventional write head is inductive.
In a disk drive using perpendicular recording the recording head is designed to direct magnetic flux through the recording layer in a direction which is perpendicular to the plane of the disk. Typically the disk for perpendicular recording has a hard magnetic recording layer and a magnetically soft underlayer. During recording operations using a single-pole type head, magnetic flux is directed from the main pole of the recording head perpendicularly through the hard magnetic recording layer, then into the plane of the soft underlayer and back to the return pole in the recording head. The shape and size of the main pole piece and associated shields are the primary factors in determining the track width.
U.S. Pat. No. 6,531,202 to Litvinov, et al. is an example of a magnetic recording medium for perpendicular or vertical recording. The medium includes a a magnetically soft underlayer deposited on the substrate. Suitable soft magnetic materials for the underlayer are said to include CoFe and alloys thereof, FeAlN, NiFe, CoZrNb and FeTaN, with CoFe and FeAlN being preferred soft materials. A magnetically hard recording layer is deposited on the soft underlayer. Suitable hard magnetic materials for the recording layer are said to include multilayers of Co/Pd or Co/Pt, L10 phases of CoPt, FePt, CoPd and FePd and hcp Co alloys, with such multilayers and L10 phases being preferred hard materials.
In U.S. published application Ser. No. 2003/0151850 by Nakamura, et al., a single pole head is described which has the main pole down-track. The main pole is composed of at least two portions where the width of the first portion continuously increases from the up-track side to the down-track side in the direction of the moving medium and the width of the second portion is the same as the width of the first portion's down-track edge in the direction of the moving medium and is constant from the up-track side to the down-track side in the medium moving direction. This is said to prevent the recording magnetic field strength from decreasing at the track edge and increases the effective track width while suppressing side-writing, thereby, realizing a magnetic recording disk apparatus with a high track density.
In U.S. Pat. No. RE33,949 to Mallary, et al. a single pole head for perpendicular recording is described which includes what is called a “downstream shield” (down-track) that is connected to the write pole at the back and separated from the write pole by a small gap at the ABS. The ABS face of the shield is designed to be many times as large as the face of the write pole section so that the density of the flux from the tip is sufficient to effect a vertical recording while the density of the flux passing into the downstream magnetic shield is low so a previously recorded pattern is not reversed or weakened.
A single pole head for perpendicular recording with the trailing shield design improves field gradients at the expense of field strength. In prior art, the trailing shield design requires either 1) a reverse flying air bearing design, or 2) the write head fabricated before the read head, or 3) elaborated processing steps to connect the trailing shield to the return pole.